GaN semiconductor devices such as, for example, light emitting diodes (“LEDs”), laser diodes, photodetectors, transistors, switches, and so forth, are widely used in many applications. Well known applications include, but are not limited to, traffic signals, mobile telephone display backlighting, liquid crystal display (“LCD”) back lighting, flash lights for cameras, and so forth. The fabrication of gallium nitride semiconductors for use as LEDs, laser diodes or lighting, gives relatively tow productivity. Also, known techniques result in semiconductor devices with a light output that is not optimised.